A fish can be a beautiful part of your household. However, it can be difficult to keep fish healthy. Even under the best of conditions, they need diligent care from their owners. You must be vigilant to ensure that your tank is free of bad water conditions and over crowding. You should also pay close attention to your fish to watch for changes that could indicate the beginning of illness.

Steps

Part 1

Getting Your Aquarium Ready for Fish

1

Purchase an aquarium that can hold at least 20 gallons. While it might seem that a big tank would only mean more work, the opposite is the case. Small tanks get dirty quicker and thus require more regular maintenance. The larger your aquarium the better. It will keep your fish happier and save you energy.[1]

20-gallon tanks are the minimum size you should consider and will be too small for many fish. Semi-aggressive fish, for example, need additional space to prevent fights. Consult with an expert about how much space your fish requires..[2]

You might be required to assemble the aquarium. Follow the instructions on the box, because these will vary from tank to tank.

Be sure that the tank comes with a lid. Many fish like to jump and can leap out of the aquarium if you aren’t careful.

You should also have a light that you leave on for approximately 12 hours a day and leave off the other half of the day. These come standard with most, but not all, aquariums.[3]

2

Purchase a heater and filter for your aquarium. These are important for keeping the aquarium at the appropriate temperature for your fish and for cleaning waste out of the water. There are many models for filters. It is principally important that you get one that is designed to a filter a tank as large as the one that you have picked out.

You should also refrain from buying an undergravel filter if you are using a fine substrate, like sand. Certain types of fish can be hurt by gravel and require a sand substrate.

A heater is especially important if you plan to keep tropical fish, because these prefer warm water.[4]

3

Purchase an appropriately sized tank stand. You will need to place your aquarium on something and most household items—desks and tables included—are not strong enough to accommodate a large tank. Unless you want to have a very expensive, fishy mess on your floor, you should buy a stand specifically designed for an aquarium of your size.

Similarly, it is a very bad idea to leave the aquarium on the floor. This will all but inevitably lead an accident. Furthermore, you won’t have much fun looking at your fish if they’re on the ground.

4

Find a safe location. A tank should be placed far away from places in the house that experience significant changes in temperature. These include areas near windows, air conditioners, radiators, and air vents. Similarly, keep the aquarium away from noise. Avoid locations near doors or in busy hallways.

For your convenience, you should also pick a location is near a power plug and a water source. You probably also want sufficient space in the area to do work on the aquarium and to observe the tank.[5]

5

Buy water treatment supplies. Your water utility probably treats its water with chemicals like chlorine that are harmful to your fish. Purchase some testing kits to determine if the water is safe. As an aquarium owner you should always keep on hand a sodium thiosulfate solution to treat chlorine and Amquel to treat chloramine.

For more information about the chemicals in your water supply, ask the local pet store owner or call your water utility.[6]

6

Put substrate and hiding places on the bottom of the aquarium. Gravel is a good, standard substrate to place on the bottom of your aquarium, though certain species might do best with sand. Tank decorations are also important for providing distraction for your fish, preventing conflict, and keeping your tank water well-maintained.

Decorations are important to the health of your fish. Because most of your fish are naturally prey, if they do not have places to hide, they will be stressed. Aggressive fish, on the other hand, will be more likely to fight without clearly delineated territory. Decorations, therefore, are important to keeping your fish healthy and encouraging them to be active. Somewhere from 50-75% cover will be good for most fish.

Fish will typically appreciate cover of any type, but some do have preferences. Fish from slow moving or static water will typically prefer soft, flexible cover like plants. Fish from the ocean or fast moving rivers tend to prefer large, hard objects.[7]

Place larger decorations toward the back and side of the tank. That way, the center of the tank won’t be obscured from your sight. These decorations can also be used to cover up things like wires and other accessories that make the tank look less appealing.[8]

7

Fill the tank. Tap water is sufficient, though you will need to treat it. Fill the water nearly, though not all the way to the top of the tank. It is necessary to keep a layer of oxygen at the top of the aquarium.[9] Cover the tank with a lid to prevent the fish from jumping out.[10]

8

Treat the water. You will probably want to add sodium thiosulfate and Amquel to the tank, and treat the tank for pH levels. A number of acids and bases can be purchased at the pet store to adjust the pH level in your tank.[11] Test the level and adjust the pH until it is appropriate for your fish.

Different fish prefer slightly different pH levels, so you should familiarize yourself with species specifications. Generally, however, somewhere from 6.8 to 7.8 is healthy for your fish.[12]

9

Cycle water for two weeks before introducing fish. After treating the water, you will want to give it sufficient time for its chemical composition to stabilize. During this period, monitor the water closely and treat if any of the readings suggest the water is inhospitable to your fish. Every couple of days do small water changes of approximately 10%.

Continue to cycle the water at a rate of approximately 10% every couple of days for the first two weeks after introducing new fish.[13]

Part 2

Introducing Fish to Your Tank

1

Verify that you are not overcrowding your aquarium. An overcrowded aquarium can become dirty. It can also encourage confrontation between fish. Unfortunately, there is no standard for determining when a tank is overcrowded, because space demands vary considerably with each individual species. Research your fish and consult with a professional.

As a rule of thumb, a 20-gallon tank can probably accommodate three to four small fish or two medium-sized fish.[14]

2

Check that your fish are compatible. Some fish require different water temperatures or substrates. Be sure that any new fish you introduce are comfortable in the same water conditions.[15] Similarly, some fish are aggressive and will have difficulty getting along with certain types of fish.

Fish aggression is highly unpredictable. However, in general, aggressive fish are most likely to fight with other fish that look similar. That is because they will be perceived as a member of the same species and thus a rival during mating season.[16]

3

Allow new fish to acclimate to tank. You do not want to keep your fish in the bag provided by the pet store for more than a couple of hours, because it will rapidly accumulate waste and become unhealthy. However, if you have the time to spare, place the bag in the water for about 15 minutes to allow the fish to acclimate to the temperature of the tank. Afterward, dump out about 20% of the water in the bag, replace it with tank water, and leave the bag in the tank for another 15 minutes. Then gently put the fish in the tank.

For more sensitive fish, you can repeat this process, replacing the water a couple of times, until the bag is predominately tank water.

This will allow your fish to become accustomed to the temperature and chemical composition of the tank.

Do not transfer any of the water from the bag into the aquarium. The water is dirty and will be unhealthy for your fish.[17]

4

Do not put in more than two fish at a time. It will take some time for your aquarium filter to adjust to the stress placed on it by the new fish.[18] For the first two weeks after you introduce new fish, do regular checks of the water and cycle in new water at a rate of about 10% every couple of days. [19]

Part 3

Maintaining Your Aquarium

1

Feed regularly. How much and what you feed your fish will vary considerably from species to species. However, you should try to get your fish accustomed to being feed at specific times during the day. You have overfed your fish if, after five minutes, any food remains in the aquarium. Refrain from overfeeding because excess food will cause the aquarium to quickly become dirty. [20]

2

Clean the tank. Remove excess food daily and use a scrapper to clean algae off from the side of the tank. Be sure to clean the bottom of the tank with a siphon to remove waste and other unsanitary leftovers. There are a variety of specialized tools available at pet stores for performing these cleanings.[21]

3

Maintain the water. Check the water frequently for pH levels and other chemical imbalances. Keep chemical treatments on hand in case the water needs to be treated.

4

Cycle water. Once every couple of weeks, you should remove and replace 10-15% of the water. Do not remove fish when changing the water. This will cause unnecessary stress. Treat new water before adding it to the tank. Use a siphon to slowly introduce the new water back into the tank.[22]

When replacing the water, put new water into a bucket that is not used for any other household tasks (cleaning products will introduce dangerous chemicals). Use this bucket as a space to test and treat the water as discussed previously. After it is treated, introduce the water into the tank.

Part 4

Dealing With Disease

1

Watch for signs of illness. It is particularly important to watch for signs of illness with fish. That is because many fish diseases are highly communicable. Take precautions if you notice:

Maintain a quarantine tank. To prevent the spread of disease, it is useful to keep a smaller tank that sick fish can be quarantined in. Keep the fish quarantined until you have diagnosed and treated the disease.

3

Visit the pet store. Most fish diseases can be treated with commercially produced anti-biotic and anti-fungal solutions. If you have been unable to determine the cause of the illness. Talk to the people at the pet store. They should be happy to offer recommendations.[24]

4

Clean the tank. To prevent further spread of illness, do everything you can to ensure that tank conditions are healthy. Clean out waste and food, check the pH, and cycle water.